Dipartimento di Agraria, Sezione di Patologia Vegetale ed Entomologia, Università di Sassari, Sassari, Italy.
PLoS One. 2018 Oct 26;13(10):e0206301. doi: 10.1371/journal.pone.0206301. eCollection 2018.
The German yellowjacket (Vespula germanica) is an opportunist predator and a scavenger, whose eclectic diet also includes honey, brood, dead and live honey-bees. There is no evidence in this species of coordinated attacks against bees involving other conspecifics, although intraspecific competition has been already reported between two or more individuals during feeding. Our aim was to gain further knowledge on the feeding behavior of V. germanica in order to evaluate its role in an apiary. Sight observations of predation and necrophagy behaviors were carried out at the ground level near hives. We also investigated how intraspecific competition can influence the feeding display in this species. Our results confirm the major role of the German yellowjacket as a scavenger, because its diet is based mostly on bee carrions. Intraspecific competition during feeding was sometimes observed. When these events occurred, the interference of another wasp led to the bee escaping only in three cases. Our study also revealed that intraspecific competition events increase when the resource is fresh (predation vs necrophagy), and that the number of competing wasps was significantly higher when the food consisted of pupae and drones, compared to adult bees. When competition involved two individuals (the most frequent case), the winner was frequently the first wasp to reach the resource in both predation and necrophagy events. This suggests that the energy invested in foraging or predating activity and in defence of prey is usually rewarded.
德国大黄蜂（Vespula germanica）是一种机会主义的捕食者和清道夫，其杂食性的食物来源还包括蜂蜜、幼虫、死蜂和活蜂。没有证据表明该物种存在涉及其他同种个体的协同攻击蜜蜂的行为，尽管已经有报道称在喂食期间，两个或更多个体之间存在种内竞争。我们的目的是进一步了解德国大黄蜂的取食行为，以便评估其在蜂群中的作用。在蜂巢附近的地面上进行了捕食和食腐行为的观察。我们还研究了种内竞争如何影响该物种的取食表现。我们的结果证实了德国大黄蜂作为清道夫的主要作用，因为它的食物来源主要是蜜蜂尸体。在喂食过程中有时会观察到种内竞争。当这种情况发生时，只有在三种情况下，另一只大黄蜂的干扰才会导致蜜蜂逃脱。我们的研究还表明，当资源新鲜时（捕食与食腐），种内竞争事件会增加，并且当食物由蛹和雄蜂组成时，与成蜂相比，竞争的大黄蜂数量明显更高。当竞争涉及两个个体（最常见的情况）时，胜利者通常是在捕食和食腐事件中第一个到达资源的大黄蜂。这表明，在觅食或捕食活动以及对猎物的防御中投入的能量通常会得到回报。
